The present invention relates to kilns. In one aspect, it relates to kilns having electronics in a control box used for controlling kiln temperature and heat cycles.
Kilns are often used for firing pottery or ceramics, both commercially and among hobbyists. Kilns are also often used in laboratories to provide specific heat cycles for forming materials and/or testing already-formed materials. Kilns are also used by custom knife artisans for creating and/or heat treating knife blades. There are many other possible uses for kilns, including but not limited to: annealing, china painting, enameling, glass fusing, glass sagging, glass shaping, heat treating, jewelry fabrication, porcelain, silver clay, and stoneware, for example. The sizes and shapes of currently available kilns vary widely. Usually, the sizes and shapes of kilns correspond to the intended use of the kiln.
Many kilns include an electronic controller for controlling parameters such as: temperature, heating time, and specific heat cycle, for example. Such electronic controllers typically include keys or buttons for inputs, a display, a circuit board, and power relays, for example. Such components of an electronic controller are often mounted in a control box. The control box is typically attached to the outside of the kiln and insulated from kiln heat to prevent damage to the components of the electronic controller.
Internal temperatures within the kiln may be as hot as 2300xc2x0 F. during operation of the kiln. Usually, thick ceramic blocks forming walls define an oven space or enclosure, and are used to confine the heat within the kiln. However, the outside surface of the kiln may still experience temperatures as hot as 400xc2x0 F. Because the components of the electronic controller are often merely inches away from the outer surface of the kiln, an insulating section is typically located between the electronic controller components and the outer skin of the kiln. Such insulating section may include a chimney structure that vents the heat from the kiln upward through the chimney and away from the electronic controller components. Such a chimney structure usually provides a path for setting up convection air currents flowing through and out of the chimney structure. Hence, the temperatures experienced by the electronic controller components will often be less than about 130xc2x0 F. The upper limit of an operating temperature range for some of the electronic controller components is typically about 150xc2x0 F.
Because the electronic controller components regularly experience temperatures near their operating temperature limits, as well as many changes in temperature as a kiln is used (i.e., many heat cycles), some of the electrical components have relatively short lives. The relays often fail most frequently and may need routine replacement if the kiln is regularly or heavily used. When a relay has failed, it is often desirable to locate the failed relay using a test probe. Conventional control boxes often must be removed or dismantled to access components of the electronic controller. This may require kiln operation down time and/or a skilled repair technician. To test the relays it is often desirable to perform a live test while the kiln is powered. However, most conventional kilns do not provide a convenient and/or safe means of performing such tests. Hence, there is a need for a way to quickly and easily access the components of an electronic controller for troubleshooting, repairing, and/or replacing such components.
U.S. Pat. No. 5,477,029 (Skutt, et al.) discloses a kiln having a control box mounted on the kiln by a hinge that pivots about a vertical axis. The control box includes a thermally insulated baffle therein, which insulates and covers the electronic components within the control box from the kiln heat. When released from being secured to the kiln, the control box is free to pivot on hinges about a vertical axis. However, most of the components of the electronic controller are not exposed and accessible when the control box is free to pivot on its hinges. To replace one of the components within the control box, such as a relay, the thermally insulated baffle will likely need to be removed and/or the control box dismantled to do so. Also, it will likely be more convenient to remove the control box from its hinges to replace a component in the control box. Also, the free swinging of the control box on its hinges about a vertical axis will likely make it difficult to safely probe testing points during troubleshooting. Hence, there is a need for an improved mounting configuration for the control box and the electronic controller components therein.
The problems and needs outlined above are addressed by embodiments of the present invention. In accordance with one aspect of the present invention, a kiln is provided, which includes an oven portion, a control box, electronic controller components, and a thermally insulating chimney portion. The oven portion has walls defining an oven space. The control box is pivotably coupled to the oven portion via a hinge at a first end of the control box so that the control box may be pivoted about the hinge from a closed position adjacent the oven portion to an open position where a second end of the control box is separated from the oven portion by a first spaced distance. The electronic controller components are attached to and located at least partially within the control box. The thermally insulating chimney portion is attached to the oven portion. The chimney portion is located between the oven portion and the electronic controller components when the control box is in the closed position. The chimney portion is separated from the second end of the control box by a second spaced distance when the control box is in the open position.
The control box is configured to pivot about the hinge along a generally horizontal axis. The kiln may further include a linkage coupled between the control box and the oven portion so that the linkage limits a pivot movement range of the control box about the hinge at the open position. A keypad and a display of the electronic controller components may be located on the second end of the control box, wherein the first end is a lower end and the second end is an upper end of the control box.
Vertical sides of the control box are separated from vertical sides of the chimney portion when the control box is in the closed position so that air channels are defined between the vertical sides of the control box and the vertical sides of the chimney portion. The chimney portion may include a first sheet metal channel attached to the oven portion, a second sheet metal channel attached to the first sheet metal channel, and a layer of insulating material attached to the second sheet metal channel. Preferably, the electronic controller components are accessible when the control box is in the open position.
In accordance with another aspect of the present invention, a kiln is provided, which includes an oven portion, a control box, and electronic controller components. The oven portion has walls defining an oven space. The control box is pivotably coupled to the oven portion via a hinge at a first end of the control box so that the control box may be pivoted about the hinge along a generally horizontal axis from a closed position adjacent the oven portion to an open position where a second end of the control box is separated from the oven portion by a first spaced distance. The electronic controller components are attached to and located at least partially within the control box.
The kiln may include a thermally insulating chimney portion attached to the oven portion, wherein the chimney portion is located between the oven portion and the electronic controller components when the control box is in the closed position, and wherein the chimney portion is separated from the second end of the control box by a second spaced distance when the control box is in the open position. The kiln may include a linkage coupled between the control box and the oven portion, with the linkage being configured to limit a pivot movement range of the control box about the hinge at the open position. Preferably, the electronic controller components are accessible when the control box is in the open position.
In accordance with yet another aspect of the present invention, a kiln is provided, which includes an oven portion, a control box, a linkage, and electronic controller components. The oven portion has walls defining an oven space. The control box is pivotably coupled to the oven portion via a hinge at a first end so that the control box may be pivoted about the hinge from a closed position adjacent the oven portion to an open position where a second end of the control box is separated from the oven portion by a first spaced distance. The linkage is coupled between the control box and the oven portion, with the linkage being configured to limit a pivot movement range of the control box about the hinge at the open position. The electronic controller components are attached to and located at least partially within the control box.